Polymer Clays are a Handful of Phthalates

Pamela Lundquist
Last Updated: Wednesday, August 01, 2007

There isn't a kid out there that doesn't enjoy molding, sculpting and squishing clay. These days, the clays of choice by kids' standards are man-made polymer modeling clays. Though polymer clays are labeled nontoxic, they may contain ingredients that could harm children.

Colorful polymer clays feel like natural clay and stay soft at room temperature, but can be easily hardened in a kitchen oven instead of a high-temperature kiln. The qualities of polymer clay are due to its primary ingredient, polyvinyl chloride (PVC)—a type of plastic also known as vinyl. PVC is considered the most toxic plastic. During manufacture and when burned, PVC creates a highly toxic byproduct called dioxin, a potent carcinogen and endocrine disruptor.

In the case of soft PVC, such as that used in polymer clay, phthalates are added to make the PVC pliable. Phthalates are a group of chemicals that have been linked with birth defects, reproductive problems, liver and thyroid damage and other health problems. Some are believed to cause cancer. Because young children tend to put toys and other objects in their mouths, many children's advocates consider vinyl toys, teethers and other vinyl children's products to pose unnecessary risk.

Tests commissioned by the Vermont Public Interest Research Group (VPIRG) showed that polymer clays may also expose children to dangerous levels of phthalates. In an effort to determine if, and how much, phthalates are found in polymer clay, as well as how exposure might occur, VPIRG sent samples of two brands of the most common polymer clays in the U.S., Fimo and Sculpey, to independent labs.

According to VPIRG's July, 2002 report, Hidden Hazards, both brands had significant levels of phthalates. Lab tests showed that Fimo brand clay contained a number of different phthalates totalling 11 to 14 percent of the total contents and the Sculpey brand consisted of 3.5 to 4.4 percent phthalates.

An assessment of real-world exposures, also conducted by an independent lab, found that clay residues containing significant amounts of phthalates were left on the hands of both children and adults after handling the clays. Phthalate residues remained on the hands even after handwashing.

When the polymer clays were baked, tests showed that phthalates contaminated the air, raising the likelihood of inhalation exposure. Clay that got too hot or burned while in the oven, released highly toxic hydrochloric acid gas due to the breakdown of the PVC.

In the report, VPIRG noted that health hazard warnings on modeling clay labels were inadequate and even misleading. Specific health effects were not listed; neither was the unique risk to pregnant women—some phthalates can cross the placenta and cause harm to the developing fetus. All clays were labeled "AP Nontoxic," a seal created by the Arts and Creative Materials Institute (ACMI), which is consortium of art and craft materials manufacturers.

Many companies, organizations and even government agencies claim that the amount of phthalates in any one consumer product is too small to cause harm. However, children are subject to multiple exposures of phthalates from different sources every day, including cosmetics and perfumes, plumbing pipes,medical devices, solvents, pesticides, food packaging and children's toys.

There are plenty of alternatives, however. Look for clays made from beeswax and other non-PVC materials. Or you can make your own with the recipes below.

Home-made Play Dough

1 cup flour
1/4 cup salt
2 tablespoons cream of tartar
1 cup water
1 tablespoon vegetable oil
food coloring (optional)

Combine all ingredients in a pot over medium heat and stir. Add food coloring until the desired color intensity is reached. (Use natural dyes like beet or berry juice for a 100 percent natural play dough.) Continue stirring until the clay forms a ball and reaches the consistency of commercial play doughs. Place on foil or wax paper until cool. Store in plastic bag or tightly sealed container.

Sand Clay- Recipe adapted from: Nature With Children of All Ages by Edith A. Sisson (Prentice Hall, 1990)
1 cup fine beach sand
1/2 cup corn starch
1/2 cup boiling water
double boiler

Mix the sand and cornstarch thoroughly in the top of the double boiler (being careful not to scratch the bottom of the pan). Pour in the boiling water and mix well. Cook in the double boiler briefly until the mixture has thickened. Should it be too thick, add a little more boiling water. Let the clay cool for a bit, and you're ready to model! Hint: Try mixing in some food coloring for variety!
When your piece is finished, put it on a flat pan or cookie sheet in a 275 degree oven until dry. You can dry it without the oven, but it will take longer.

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